Mortgage affordability calculator
Estimate your borrowing range from income, deposit and existing commitments, and see the monthly repayment that comes with it.
How this is calculated
Most lenders start from a multiple of gross income, commonly between 4 and 4.5 times, with higher multiples reserved for higher earners or specific professions.
Existing monthly credit commitments are annualised and taken off your income before the multiple is applied, which is why a car finance agreement can cost you far more in borrowing power than its monthly figure suggests.
The monthly repayment shown is a standard capital and interest calculation over the term you enter. It excludes buildings insurance, service charges and ground rent.
A real lender decision also runs an affordability stress test at a rate higher than the one you are offered, so treat this as an upper bound rather than a target.
Rates used · 2026/27
| Typical income multiple | 4.0x to 4.5x |
| Higher-income multiple | up to 5.5x |
| Standard term | 25 to 35 years |
| Deposit for best rates | 25% or more |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
On a combined £45,000 income with £250 a month of commitments, £3,000 a year comes off, leaving £42,000 assessed. At 4.5x that is £189,000 of borrowing, and with a £40,000 deposit an indicative price of £229,000 at 82.5% loan to value.
Common questions
Why does my student loan reduce what I can borrow?
It is a fixed monthly deduction from your pay, so lenders treat it as a committed outgoing in the affordability assessment.
Is this the same as a decision in principle?
No. A decision in principle is a soft check by an actual lender against their own criteria. This is arithmetic on a rule of thumb.
Does a bigger deposit increase what I can borrow?
Not usually. It increases the price you can reach and improves the rates available to you, but the borrowing itself is still capped by income.
What loan to value should I aim for?
Rates generally improve at 90%, 85%, 80% and 75% loan to value. Crossing one of those thresholds is often worth more than a slightly larger loan.